Hindawi
Journal of Food Quality
Volume 2022, Article ID 1274679, 7 pages
https://doi.org/10.1155/2022/1274679
Research Article
Effects of Pretreatment and Drying on the Volatile Compounds of
Sliced Solar-Dried Ginger (Zingiber officinale Roscoe) Rhizome
Roseline Esi Amoah ,1 Faustina Dufie Wireko-Manu ,2 Ibok Oduro ,2
Firibu Kwesi Saalia ,3 WilliamOtoo Ellis ,2 Alexander Dodoo ,1 Charles Dermont ,4
and Maame Ekua Manful 5
1Ghana Standards Authority, Accra PMB MB 245, Ghana
2Department of Food Science and Technology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
3Department of Food Process Engineering, P. O. Box LG 77, University of Ghana, Legon, Accra, Ghana
4Graduate School of Agriculture and Bioengineering, JUNIA ISA, Lille, France
5School of Food Science and Environmental Health, Technological University Dublin, Dublin, Ireland
Correspondence should be addressed to Roseline Esi Amoah; rosarchie@yahoo.com
Received 14 October 2021; Revised 2 December 2021; Accepted 10 December 2021; Published 8 January 2022
Academic Editor: Flora V. Romeo
Copyright © 2022 Roseline Esi Amoah et al.%is is an open access article distributedunder theCreativeCommonsAttributionLicense,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Ginger (Zingiber officinale Roscoe) rhizomes are mostly used as spice and medicine due to their high aroma intensity and
medicinal bioactive compounds. However, the volatile compounds of ginger, partly responsible for its aroma and medicinal
properties, can be affected by the pretreatment, drying method, and extraction processes employed.%e objective of this study was
to assess the effects of pretreatment and drying on the volatile compounds of yellow ginger variety at nine months of maturation.
%e effect of potassium metabisulfite (KMBS) and blanching pretreatment and drying on the volatile compounds of ginger using
head space solid-phase microextraction with GCMS/MS identification (HS-SPME/GCMS/MS) was investigated. KMBS of
concentrations 0.0 (control), 0.1, 0.15, 0.2, and 1.0% and blanching at 50°C and 100°C were used for pretreatment and dried in a
tent-like concrete solar (CSD) dryer and open-sun drying (OSD). %e different concentrations of KMBS-treated fresh ginger
rhizomes did not result in any particular pattern for volatile compound composition identification. However, the top five
compounds were mostly sesquiterpenes. %e 0.15% KMBS-treated CSD emerged as the best pretreatment for retaining
α-zingiberene, β-cubebene, α-farnesene, and geranial. %e presence of β-cedrene, β-carene, and dihydro-α-curcumene makes this
study unique. %e 0.15% KMBS pretreatment and CSD drying can be adopted as an affordable alternative to preserve ginger.
1. Introduction subjects it to microbial contamination [6], and this requires
pretreatment in addition to regular cleaning protocols to re-
Ginger (Zingiber officinaleRoscoe) is a rhizome of the aromatic duce the microbial load [1]. Several pretreatment methods
Zingiberaceae family mainly used as a spice [1]. It possesses involving the use of both chemical (sodium hydroxide
strong pungent [2] and unique flavour components which are (NaOH)), sodium chloride (NaCL), potassium hydroxide
dominated by α-zingiberene, α-curcumene, α-farnesene, (KOH), sulfites, sodium metabisulfites (NaMBS), and potas-
β-sesquiphellandrene, β-bisabolene, geranial, and neral or sium metabisulfites (KMBS)) and physical (thermal blanching
Citral [3]. It is also used as herbal medicine due to its phenolic (hot water, steam, superheated steam, etc.)) treatment have
components such as gingerol, paradol, shogaol, and zingerone been applied to foods. In addition, nonthermal treatments such
[4]. %e amounts of these flavour components vary widely as ultrasound and freezing [1] have been applied to agricultural
depending on the variety and processing methods used on the produce during processing such as drying with varying effects
rhizome, especially the extraction and detection methods [5]. on the product characteristics and on consumer acceptability of
%e subterranean environment of the rhizome before harvest the final product. Apart from reducing microbial load,
2 Journal of Food Quality
pretreatment of agricultural produce is frequently done to producing areas of Nkawie in the Ashanti region of
minimize colour and or texture changes during drying [1]. Ghana. %is is a town situated on latitude of 6° 39′
Blanching of ginger has been done at a temperature of 70°C for 59.99″ N and longitude of −1° 48′ 59.99″ W. %e fresh
a maximum duration of 30min which reduced the pungent ginger rhizomes were transported (6 hours) to the
compound, gingerol, drastically [7]. %e ginger volatile oils laboratory packed in a perforated nylon sack (to fa-
containing the flavour components are also reduced upon heat cilitate aeration).
treatment just as the gingerol responsible for the pungency
[8, 9]. A pretreatmentmethod that has frequently been used for
agricultural produce including ginger without heat application 2.2. Washing and Pretreating Fresh Ginger. %e fresh raw
is the use of dilute potassium metabisulfite (KMBS). Washing ginger was soaked in water for two hours to remove the
in dilute potassium metabisulfite has the additional advantage adhering sand/debris and washed vigorously three times
of reducing the microbial load as well as increasing the anti- each time with fresh water. %e washed ginger rhizomes
oxidant activity of the product. It also partly preserves the were sliced manually with a kitchen knife to a thickness
ginger flavour compounds [10]. of 3–5 mm. %e sliced ginger was washed again in water.
In addition to producing dried ginger of acceptable %e sliced ginger was divided into seven parts; four parts
microbial safety, colour, and texture, the pretreatment and were soaked separately in 0.1%, 0.15%, 0.2%, and 1.0%
drying methods used must also preserve the volatile com- potassium metabisulfite (KMBS) concentrations for 5
pounds. Flavour components in any food product are af- minutes. Another one part was soaked in water for 5
fected by the drying method [9, 11]. Harsh drying methods minutes serving as control. %e final two parts were° °
that use elevated temperatures beyond 60°C may negatively blanched at 50 C and 100 C temperatures for 5 minutes
affect the flavour of ginger [8, 9, 12]. Hence, the use of and 60 seconds, respectively. %e pretreated sliced gin-
pretreatment and dryingmethods in the processing of ginger ger rhizomes were drained separately and sampled for
rhizomes must be carefully selected to achieve dried ginger analyses of the volatile compounds’ composition using
which contains the dominant volatile compounds. HS-SPME/GCMS.
%e methods for extraction and analyses of volatile com-
pounds are also important. Solid-phase microextraction 2.3. Drying of Fresh Washed Sliced Ginger. %e remaining
(SPME) is a simple, sensitive, and solvent-free technique which sliced ginger of each pretreatment was divided into two
integrates sampling, isolation, and concentration of analytes parts: one part was dried in the concrete solar dryer
from samples into a single-step process making it a fast and (CSD) (Figure 1) and the other part was dried in the
inexpensive sampling method [13]. Head space solid-phase open sun (OSD) for five days. %e temperatures and
microextraction (HS-SPME) is a method used in determining humidity ranged 29.0–52.50°C; 27–91.5% RH, and
the flavour compounds of several products including ginger oil. 28.0–55.5°C; 29.5–90.5% RH for the CSD and OSD,
Yang et al. [14] analysed oven-dried ginger by HS-SPME and respectively, using a digital temperature-humidity data
detected chiefly α-zingiberene (26.4%), sesquiphellandrene longer (HOBO pro v2 digital logger (Model U23-001,
(10.2%), β-phellandrene (10.0%), camphene (7.6%), geranial USA) (Appendix 1). %e dried sliced ginger was further
(6.6%), α-curcumene (6.0%), and β-bisabolene (5.4%). Similar analysed for volatile compounds composition using
work repeated with varying oven temperatures and drying HS-SPME/GCMS.
methods, such as microwave drying, freeze drying, silica gel
drying, and vacuum drying, detected similar top 5 volatile
compounds but with varying concentrations [3, 11]. 2.4. Preparation of Ginger for the Head Space Solid-Phase
In most African countries and other tropical developing Microextraction (HS-SPME) Analysis
economies, industrial dryingmostly involves the use of electrical 2.4.1. Pulverising and Milling of Ginger. All pretreated and
energy which comes with additional cost, while most traditional untreated fresh ginger rhizomes were pulverised using a
approaches use open-sun drying. However, the solar drying Moulinex blender (DPA141/35H-0517 R, France) for ap-
approach could be an alternative process relative to the open- proximately 45 s and used for analysis. Pretreated and un-
sun drying. Solar drying has the advantage of reducingmicrobial treated sliced dried ginger were milled to pass through a
load and environmental contamination associated with open- sieve size of 1mm using Moulinex mill (DPA141/35H-
sun drying [15]. Nonetheless, there is a paucity of data on the 0517 R, France).%e pulverized fresh andmilled dried ginger
effects of solar drying and pretreatment on the flavour profile of samples were stored in plastic vials at −18°
ginger rhizomes. %us, this study assessed the effects of pre- C until used for
treatment (soaking in dilute solutions of potassiummetabisulfite analysis.
(KMBS) and blanching) and drying on the volatile compounds
of yellow ginger variety at nine months of maturation. 2.4.2. HS-SPME/Gas Chromatography-Mass Spectrometry
(GC-MS) Analysis. %e choice of an SPME fibre is essential
2. Materials and Methods because it may affect the type of compounds isolated.
According to Ding et al. [11], a 100 µmpolydimethylsiloxane
2.1. Source of Raw Materials. Eighty kilograms (80 kg) of (PDMS) fibre proved to be the most useful in the extraction
fresh yellow ginger rhizomes at nine months of ma- of ginger volatiles when compared to 30 μm PDMS, 75 µm
turity were purchased from an outgrower in the ginger carboxen polydimethylsiloxane (Carboxen PDMS), and
Journal of Food Quality 3
Figure 1: Pictorial representation of the concrete solar dryer (CSD).
Table 1: Major volatile compounds detected in pretreated sliced fresh yellow ginger rhizome.
Fraction (%)
Retention time (min) Compound name Potassium metabisulfite concentration Blanchingtemperature
Control 0.10% 0.15% 1% 0.20% 50°C 100°C
8.69 α-Pinene 1.346
8.98 Camphene 0.008 2.644 2.139 1.786 5.178 0.029
10.85 α-(E)-Sabinene hydrate 0.015 4.136 3.417 3.706 6.196 0.050 0.099
15.16 Neral 1.351
15.18 cis-Z-α-bisabolene epoxide 1.235
15.19 2,6-Octadienal, 3,7-dimethyl (Z) 0.032
15.73 Geranial 0.008 2.647 2.231 3.156 0.037 0.052
15.74 Dill-apiole 2.298
21.99 α-Curcumene 0.014 4.192 32.920 4.294 16.827 0.488 0.665
22.18 Germacrene D 2.301 0.030 0.051
22.22 α-Cubebene 0.015 2.600 3.519
22.61 α-Zingiberene 32.983 13.935
22.62 Dihydro-α-curcumene 99.768 33.943 5.718 97.898
22.87 α-Farnesene 0.040 12.149 11.103 0.154 0.266
23.03 α-Bisabolene 0.040 5.885 8.089 10.686 98.821
23.07 α-Bisabolene 7.648
23.20 (+)-Epibicyclosesquiphellandrene 0.983
23.48 δ-Carene 15.441
23.52 α-Cedrene 0.046 15.614 4.171 16.213 21.543 0.201 0.159
24.75 c-Gurjunene 0.006 0.945 0.723
26.17 Zingerone 0.037
65 μm polydimethylsiloxane divinylbenzene (PDMS-DVD). %eGas Chromatography coupled toMass Spectrometry
%e volatile components of ginger samples were extracted by (GC-MS/MS) was used to identify the major compounds of
head space solid-phase microextraction (HS-SPME) with a the dried ginger. A Varian VF-1ms capillary column
100 µm length PDMS fibre column (Supelco, USA). Pre- (30m× 0.25mm) attached to a Varian CP 3800 gas chro-
liminary analysis on this fibre gave an optimum temperature matography and a Varian Saturn 2000 spectrometry was
of 50°C at 23min extraction time for α-zingiberene, α-far- used for the separation of the various components. %e
nesene, α- curcumene, β-bisabolene, and β-cedrene. temperature gradient was as follows: 40°C (3min), 130°C at
Approximately 1 g of pulverised fresh ginger or milled 7°C/min (3min), 220°C at 3°C/min (2min), and 260°C at
dried ginger was weighed into a 10mL amber glass vial. %e 10°C/min (5min). %e flow rate of the helium gas was 1mL/
fibre of 100 μm diameter was manually inserted into the min and the fibre was introduced and injected at 230°C
septum of the amber glass vial in the hot air oven at 50°C for without split (split off). %e compounds were identified by
23min and allowed for adsorption. %e fibre was removed comparing the mass spectra of the chromatographs with
after adsorption and manually injected into the Gas built-in libraries with authentic standards. %e relative
Chromatography-Mass Spectrometry (GCMS) (Varian CP- percentage amount of each component was calculated by
3800/3380, Walnut Creek, CA 94598 United States of comparing its average peak area with the total area of the dry
America). weight base.
4 Journal of Food Quality
Table 2: Major volatile compounds detected in pretreated sliced solar dried yellow ginger rhizome.
Fraction (%)
Retention time (min) Compound name Potassium metabisulfite concentration Blanchingtemperature
0.0% 0.10% 0.15% 0.20% 1% 50°C 100°C
8.69 α-Pinene 4.860 0.003
8.98 Camphene 2.9685 1.32 0.005 0.007
10.82 α-Phellandrene 4.3375
10.85 α -(E)-Sabinene hydrate 2.96 0.011 3.034 0.006
15.16 Neral 1.70 0.002 0.002
15.18 Z,Z,Z-4,6,9-Nonadecatriene 0.005 0.007
15.19 2,6-Octadienal, 3,7-dimethyl (Z) 0.001
15.55 Borneol 0.001
15.73 Geranial 2.5272 2.61 11.718 0.017 3.122 0.003 0.003
15.74 Dill-apiole 0.005
21.29 α-Farnesene 0.0055
21.99 α-Curcumene 5.9425 4.89 0.008 4.888 0.006 6.433
22.18 Germacrene D 2.5849 2.86 0.081 0.115 2.964
22.22 α-Cubebene 31.813 44.703 3.462 0.003
22.61 α-Zingiberene 19.377 0.028
22.62 Dihydro-α-curcumene 39.719 41.40 41.017 43.035 44.523
22.87 α-Farnesene 15.536 16.20 17.073 16.459 17.137
23.03 α-bisabolene 9.2911 9.69 10.194 10.130 10.963
23.07 (6R,7 R)-bisabolene 36.948 55.046
23.20 Epibicyclosesquiphellandrene 0.002
23.52 α-Cedrene 17.073 19.14 20.231 19.490 20.911
24.75 c-Gurjunene 0.012
26.17 Zingerone 0.004
3. Results and Discussion rhizome did not show any particular pattern in the isolation
of volatile compounds as the concentrations increased from
%e major volatile compounds identified are presented in 0.1% to 1.0%; however, the presence of α-zingiberene in
Tables 1–3 and the HS-SPME/GCMS chromatograms in higher quantities in the 0.1% KMBS-treated fresh ginger
Appendix 2. %e fresh control retained chiefly dihydro- makes it more superior than the other concentrations and
α-curcumene (99.78%), which is quite different compared to even the control of this study [16]. %is shows that KMBS
the compounds retained in the KMBS-pretreated fresh pretreatment had more diversified top five volatile com-
ginger rhizomes. Potassium metabisulfite-treated fresh pounds than the control.
ginger samples recorded α-Curcumene, α-Zingiberene, %e control of the fresh sample behaved similarly to the
β-Cedrene, σ-Carene, α-Bisabolene, and β-Bisabolene in blanched samples by detecting one major volatile com-
different quantities as shown in Table 1. pound. %e 100°C sample retained dihydro-α-curcumene as
%e preservation of dihydro-α-curcumene (99.78%) as the major component (97.9%) just as the control, while the
the major component in the fresh sample was totally dif- 50°C blanched sample had β-Bisabolene as the major
ferent from the findings of similar work done [11] that component (98.8%). %is could affect the flavour of the
detected compounds such as α-zingiberene (28.12%), blanched samples immensely because the compounds pre-
β-citral (15.71%), α-farnesene (6.90%), β- sesquiphellan- served in a ginger sample together contribute to its unique
drene (7.65%), and α-curcumene (2.84%). %e difference flavour. %e blanching temperature of 50°C and 100°C were
may be attributed to the differences in methodology and the chosen based on the loss of gingerol beyond heat application
source of the ginger. On the other hand, the samples treated of 60°C [12]; also the traditional processors boil the ginger
with KMBS shared similar volatile compounds, especially rhizomes for 10min to cure it before drying, hence 100°C to
0.1% which had higher α-Zingiberene (33%) and α-Farne- ascertain its effect. %e preservation of one major dominant
sene (12.15%) compared to the findings of Ding et al. [11]. volatile compound in the fresh and blanched ginger rhizome
Again, the retaining of high dihydro-α-curcumene which of this study is similar to the findings of some work done [17]
has the same molecular weight and formula as α-zingiberene retaining zerumbone (85–87%) as the single major volatile
in the control (0.0% KMBS) may be due to harsh extraction compound in fresh ginger rhizomes using the hydro-
conditions and possibly the temperature. α-zingiberene is a distillation method.
sesquiterpene compound, unique to ginger, and was %e effect of drying on the volatile compounds is shown
retained in 0.1% and 1.0% KMBS-treated fresh ginger in in the differences between the fresh control and the control
quantities of 33% and 13.94%, respectively. %e use of solar dried and open-sun-dried samples. %e fresh control
different concentrations of KMBS to pretreat the ginger detected only dihydro-α-curcumene (99.8%) as shown in
Journal of Food Quality 5
Table 3: Major volatile compounds detected in pretreated sliced open-sun dried yellow ginger rhizome.
Fraction (%)
Retention time (min) Compound name Potassium metabisulfite concentration Blanchingtemperature
Control 0.10% 0.15% 0.20% 1% 50oC 100oC
8.69 α-Pinene
8.98 Camphene 2.1371 0.003 4.292 5.547 0.003 1.333 0.003
10.89 trans-4-%ujanol 4.1767 5.338 5.893 8.300 0.006 1.992 4.866
15.16 Neral 0.0014
15.19 2,6-Octadienal, 3,7 -dimethyl (Z) 0.002 0.001 0.001
15.55 Borneol
15.73 Geranial 2.6124 0.003 0.003 0.004 0.003 0.001 0.002
21.99 α-Curcumene 5.9455 6.917 6.052 9.391 0.009 2.656 5.681
22.18 Germacrene D 0.004 0.003
22.22 α-Cubebene 2.7886 0.003 0.003 0.004 1.149
22.61 1,3, 6,10-Dodeca tetraene,3, 7,11-trimethyl (Z, E)- 40.171
22.61 α-Zingiberene 39.641
22.62 Dihydro-α-curcumene 41.941 6.326 58.085 17.546 42.915
22.87 α-Farnesene 15.57 16.653 15.126 25.222 0.023 62.812 16.487
23.03 α-Bisabolene 9.3904 10.091 9.633 15.520 14.397 4.250 10.215
23.52 α-Cedrene 17.72 19.032 18.813 29.651 27.440 8.252 19.811
36.52 Caryophyllene oxide 0.004 0.002
Table 1, but the solar dried and open-sun-dried samples method of extraction as well as the drying methods used
showed differences in the top 5 compounds detected. In the [5, 9, 18]. Apart from the top 5 compounds, CSD and OSD
CSD samples, compounds detected were dihydro-α-curcu- shared Camphene (2.97%; 2.145%) and Geranial (2.53%;
mene (39.72%), α-farnesene (15.54%), β-bisabolene (9.69%), 2.61%) in similar quantities.
α-curcumene (5.94%), and β-phellandrene (4.34%) as shown %e combination of pretreatment and drying affects the
in Table 2. flavour compounds. KMBS is used in preserving the colour
%e detected compounds were different from the find- [19] of a product and to reduce and/or prevent microbial
ings of one study that [14] reported mainly zingiberene, proliferation. However, the residual sulfur dioxide (SO2)
β-sesquiphellandrene, α-farnesene, and β-bisabolene or may affect the final flavour [20] underscoring the need for
α-curcumene from air-dried ginger rhizome using the same the application of the right concentration. In this study, the
fibre but different temperature and extraction time.%e CSD results showed that drying and pretreatment affected the
samples also showed remarkable differences between the volatile compounds isolated, which gives the unique final
findings of some studies done [3, 11]. %ey reported that flavour of the dried ginger rhizome. %e 0.1% and 1.0%
drying increased or decreased certain volatile compounds KMBS-treated samples showed minor differences in the top
affecting the overall flavour. Irrespective of the drying 5 compounds isolated from the fresh and dried samples.
method employed in their study, similar dominant volatile %ese concentrations showed only one compound which
compounds were isolated but in different quantities. was found in the fresh but not in the dried samples.
%erefore, the observed differences in findings of this study α-zingiberene (33%) was isolated in the fresh 0.1% KMBS
relative to the other studies may be attributed to differences samples but not in the dried samples. %is may have
in extraction time and temperature [14] and/or variety of decomposed to dihydro-α-curcumene of 41.40% for CSD
ginger. %e results also showed differences between the CSD and of 41.94% for OSD, respectively (Bartley and Foley,
and OSD compounds, with about 40% of α-zingiberene 1994). Considering the detected volatile compounds for the
(39.64%) being retained in OSD. %e presence of this 0.1% KMBS-treated samples, the dried samples had higher
compound is the mark of quality making the difference quite quantities than the fresh samples such as β-cedrene (15.6;
remarkable. %e following compounds were also isolated: 19.14; 19.03%), α-farnesene (12.15; 16.20; 16.65%), β-bisa-
α-curcumene (5.95%), α-farnesene (15.57), β-bisabolene bolene (5.89; 9.96; 10.09%), and α-curcumene (4.19; 4.89;
(9.39%), and trans-4-thujanol (4.18%) (Table 3). %us, the 6.92%) for the fresh, CSD, and OSD, respectively.%is agrees
characteristics of the OSD samples in terms of active with some findings [11] that drying causes the reduction or
compound composition were relatively more like the increase of certain volatile compounds. For the 1.0% KMBS
findings of Yang et al. [14], in retaining compounds such as samples, dihydro-α-curcumene, β-cedrene, β- bisabolene,
α-zingiberene (53.12%), curcumene (4.9%), α-farnesene and β-carene were common to the fresh and dried samples
(8.61), β-bisabolene (5.98%), and β-sesquiphellandrene but in different quantities as shown in Tables 1–3. However,
(13.03%), than when compared to the CSD samples. %e in this treatment, while α-Zingiberene (33.9%) was isolated
differences were in the quantities which may be due to the in the fresh samples, α-farnesene was peculiar to the dried
variety and age of ginger rhizome or the differences in samples. Both α-zingiberene and α-farnesene are
6 Journal of Food Quality
sesquiterpenes with the same molecular formula and weight. %e presence of β-cedrene, β-carene, and dihydro-
%erefore, the effect of both KMBS and drying may account α-curcumene isolated among the top 5 volatile compounds
for this difference. for the yellow variety makes this study unique from most
%e volatile compounds of the 0.15% and 0.2% work done using HS-SPME [3, 11, 14].
KMBS-treated samples showed a different pattern relative to
the 0.1% and 1.0%KMBS-treated samples.%e 0.15% and 0.2% 4. Conclusion
KMBS-treated samples had more differences in the detected
compounds. In these treatments, the fresh samples had more %e effect of pretreatment with KMBS resulted in the ap-
similar compounds to the OSD samples than the CSD. pearance and disappearance of certain volatile compounds
α-Bisabolene was the only common compound present in the compared to the control. %e different concentrations of
fresh (7.65%) and CSD (36.95%) for the 0.15% KMBS-treated KMBS treated with fresh ginger did not result in any par-
but in the 0.2% KMBS-treated samples, and the fresh samples ticular pattern. However, α-zingiberene was detected from
shared no common compound with the CSD as shown in 0.1% to 1.0% treated samples, which is the mark of quality
Tables 1 to 3. %e 0.15% fresh samples shared β-cedrene (4.17; ginger oil, making 0.1% superior to a higher α-zingiberene
18.81%), α-farnesene (11.10; 15.13%), and α-curcumene (32.9; fraction and recommended for fresh ginger preservation.
6.05%) with the OSD, respectively. %e 0.15% KMBS-treated Both blanched samples of 50°C and 100°C detected only
CSD was the only KMBS dried sample that isolated α-Zin- dihydro-α-curcumene and β-bisabolene, which may affect
giberene (19.38%) apart from the OSD dried control which is a the overall flavour of the product. Drying alone showed OSD
mark of good quality ginger oil because it gives the specific and CSD samples as having similar volatile compounds, yet
ginger aroma [21] as well as compounds such as α-bisabolene OSD was seen to be better for detecting a higher α-zingi-
(36.95%) and geranial (11.72%) which give ginger rhizome the berene fraction. On the other hand, the combination of
“citrus-like” flavor (Bartley and Foley, 1994).%is study reports pretreatment with KMBS and drying or blanching and
that 0.15% treated CSD sample is more superior to all dried drying showed the appearance and disappearance as well as
samples irrespective of the drying method or pretreatment increase and/or decrease of certain volatile compounds,
used. Even though the OSD control may be considered su- which will determine the flavour of the dried ginger rhi-
perior for having higher α-zingiberene (39.64%), research zomes. %e 0.15% KMBS-treated CSD emerged as a better
showed that this particular treatment had the highest yeast and dried pretreatment for retaining α-zingiberene, β-cubebene,
mould contamination [1] which is unsafe for human α-farnesene, and geranial. None of the blanched dried
consumption. samples detected α-zingiberene using HS-SPME/GCMS/MS
Blanching is a heat treatment that is used mostly to and as such it is not a good pretreatment method for ginger
reduce drying time and microbial load. However, the high rhizomes when flavour preservation is the objective. %e
heat treatment regime for blanching can cause a change in tent-like concrete solar dryer can be adopted for commercial
the chemical composition of ginger rhizome, reducing both ginger drying with 0.15% KMBS pretreatment to preserve
the pungency and flavour or altering it greatly [7]. Blanching the volatile compounds of ginger. %e limit of this study
and drying had a great effect on the volatile compounds. lies in the solar drying methods not being as controlled as
Blanching at 50°C for 5min and 100°C for 60 s for the fresh mechanical dryers would have been. Nonetheless, the
samples detected only onemajor volatile compound which is study was targeted at farmers and processors as a more
α-Bisabolene (98.82%) and dihydro-α-curcumene (97.90%), affordable ginger preservation method than the me-
respectively. On the other hand, the blanched, CSD, and chanical dryers. It is expected that farmers and processors
OSD samples showed similar top 5 compounds, namely, would adopt the use of this cost-effective method. It is also
dihydro-α-curcumene, β-cedrene α-farnesene, β-bisabolene, important to consider studies on suitable packaging materials
and α-curcumene in spite of the temperature differences. in the future.
%e CSD 50°C samples showed similar compounds in almost
equal quantities relative to the CSD 100°C samples (Table 2).
%is implies that the temperature of the blanched samples Data Availability
for CSD did not make much difference in the volatile Data are deposited in a repository.
compound composition as well as the quantities for both
temperatures (dihydro-α-curcumene (43.04; 44.52%), Conflicts of Interest
β-cedrene (19.49; 20.91%), α-farnesene (16.45; 17.14%),
β-bisabolene (10.13; 10.96%), and α-curcumene (4.89; %e authors declare no conflicts of interest for the content
6.43%) for 50°C and 100°C, resp.). %e pattern was different published in this manuscript.
for the OSD samples for different temperatures as they gave
different quantities of volatile compound (Table 3). Acknowledgments
On the whole, none of the blanched samples, fresh or
dried, retained α-zingiberene, which is the mark of quality %e authors are very grateful to the management of ISA Lille
ginger oil using HS-SPME. %e absence of α-zingiberene Catholic University, Food Science Department, Lille, France,
from the blanched samples in this study reduces the quality for making their laboratory facilities available for this re-
of the samples and as such it is not a recommended choice of search. %is work was financially supported by the Ghana
pretreatment for ginger. Standards Authority, Ghana. %e head of the funding
Journal of Food Quality 7
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